Since 1840, Mexico City has been sinking further and further. On the one hand, the subsidence is due to natural compaction (i.e., the overlaying of geological strata). However, in addition to natural extraction, the main cause of deformation is water pumping.[1] Previous studies found that Mexico City is subsiding by up to 40 cm per year.[2] Intensive subsurface extraction is causing piezometric reduction and an increase in effective stresses in the subsurface, resulting in compaction and ground subsidence of extraordinary magnitude.[3] Considerable structural damage has been observed in the area. This structural damage is often associated with major risks and can lead to accidents such as the metro collapse in 2021.[4] Soil subsidence risk maps are a valuable decision-making tool to help local governments develop better risk management, land use, and mitigation strategies for cities with severe soil subsidence. Therefore, the main objective of the study is to estimate the subsidence rate for Mexico City in 2022 and to estimate the risk as a function of subsidence rate and population density. For this purpose, InSAR ground subsidence data from two Sentinel-1 images were processed using the ESA SNAP 9 platform. Census data from the Instituto Nacional de Estadística y Geografía (INEGI)[5] were also used. The estimation of risk classes was performed with QGIS 3.28.3.
In the eastern part of Mexico City, rapid land subsidence is occurring due to the over-exploitation of groundwater resources and the resulting compaction of clayey lacustrine sediments [6] According to the subsidence map derived from the Sentinel-1 data, the areas with higher rates of land subsidence are also located in the eastern part and in some parts south of the city, with subsidence values of up to almost 6 cm within 5 months. (Figure 1) These areas have the highest values of land subsidence, likely caused by the combination of lacustrine deposition with high groundwater withdrawal rates.